Preview a markdown card with specified style (returns base64 image)
AI agents call preview_card to retrieve information from Markdown to Card - MCP工具 without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The 'preview_card' tool generates and returns a preview (base64-encoded image) of a markdown card in a specified style. This is fundamentally a retrieval/generation operation with no side effects—it does not create permanent artifacts, delete data, execute arbitrary code, or move money. The tool is designed to let users see what a card will look like before committing to generation.
From the tool's definition Tool name 'preview_card' with description 'Preview a markdown card with specified style (returns base64 image)' indicates a read-only operation that retrieves a preview image without persisting it or modifying data.
Attacks that exploit this kind of access
Preview a markdown card with specified style (returns base64 image). It is categorised as a Read tool in the Markdown to Card - MCP工具 MCP Server, which means it retrieves data without modifying state.
Register the Markdown to Card - MCP工具 MCP server in PolicyLayer and add a rule for preview_card: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Markdown to Card - MCP工具. Nothing to install.
preview_card is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the preview_card rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for preview_card. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
preview_card is provided by the Markdown to Card - MCP工具 MCP server (jasperjeje/mdtcard). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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